Investigation of Cu ion drift through CVD TiSiN into SiO2 under bias temperature stress conditions

Abstract

Cu gate metal oxide semiconductor (MOS) capacitors with and without thin chemical vapor deposition (CVD) TiSiN diffusion barrier were subjected to bias temperature stress (BTS) conditions. Cu drift flux for the MOS capacitor with CVD TiSiN diffusion barrier was about one order of magnitude smaller than that without the diffusion barrier. The activation energy of the drift flux was larger by a factor of 1.5 than that without the diffusion barrier. Cu thermal diffusion in the CVD TiSiN is dominant for Cu ion drift into the plasma enhanced (PE)-CVD SiO2. The Cu concentration depth profile in SiO2 showed that the Cu dose in PECVD SiO2 under thermal stress is significantly smaller than that under BTS conditions.